Forward impacted plow for trenchers

ABSTRACT

A plow trenching apparatus for a vehicle having a raisable boom and a trenching plow pivotally mounted at a distal end of the boom in a plow holder, to extend rearwardly and downwardly therefrom. The plow has an upper portion and a lower portion, with a forwardly protruding toe portion, and a forward facing cutting portion. The plow is pivotable in the holder about a pivot axis located behind the holder and behind the plow, as seen in the travel direction of the plow during operation. A pivoting motion is imparted to the plow by a vibrator arranged at the upper portion. The vibrator is arranged to impart vibrations generally in a vertical plane, so that the lower portion is pivoted generally back and forth in the travel direction. The vibrator can be located behind or in front of the upper portion. The vibrator can have two eccentric weights, each being rotatable around its axis in a plane, the two weights being synchronized in their rotation so that they pass and are 180 degrees apart at two points during the rotation. This arrangement creates a straight line oscillating motion in the plane. A hydraulic cylinder is connected between the blade holder and the plow blade to set the depth of the plow.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates generally to trenching equipment and more particularly to holders for plow blades of the type used to rip a trench for the laying of cable, drainage pipe or other items. The apparatus is attached to a carrier vehicle, such as a tracked vehicle. More specifically, the trenching apparatus incorporates a vibrating mechanism arranged to vibrate the plow.

[0003] 2. Description of the Prior Art

[0004] In the past, different approaches have been tried to perform the trenching and cable/pipe laying operations in one operation.

[0005] The blades of prior art plows, trenchers, rippers and the like are generally connected behind a tractor at a fixed height, such that they may be forced along a path through the ground to generate a cut of fixed depth in the ground. Manual adjustment of the height of the blade is known. In U.S. Pat. No. 4,219,947 and corresponding Canadian patent no. 1,075,479, for example, a blade dog pivotally mounted on the blade holder is provided to lock the blade in the holder at selected heights by virtue of complementary recesses formed in the blade shank at various heights.

[0006] Manual adjustment in the prior art requires significant expenditures of time and effort in order to adjust the height of blade.

[0007] In some equipment, the height of the blade holder can be varied by moving the boom which supports the blade holder. However, this is an undesirable way of adjusting the height of the blade, since it is important for maximum pulling power and efficiency that the boom should be essentially horizontal.

[0008] An especially beneficial arrangement of an adjustable blade holder is shown in U.S. Pat. No. 5,090,141. The plow is held in a holder which is pivotably arranged on arms attached to a vehicle. The plow is movable in the vertical direction with regard to the holder using, for example, a hydraulic cylinder. In this way, the position of the plow blade can be adjusted relative the holder to effectively change the depth of the plow cut in the soil.

[0009] To enhance the trenching power of a plow, it is known to use a vibrator to impart vibrations to the plow and especially the cutting edge thereof. One vibrating cable plow is shown in U.S. Pat. No. 4,867,607. A vibrator, specifically an eccentric hydraulic vibrator, is arranged on top of the plow blade holder, i.e. at an end of the plow blade holder furthest away from the soil or ground. Vibrations will be of generally random nature using this type of mechanism, making vibrations spread over the entire vehicle, necessitating the use of a dampening mechanism arranged between the plow and the carrier vehicle.

[0010] Another type of vibrating plow is shown in U.S. Pat. No. 4,087,982, wherein a vibrator is arranged to vibrate a plow in a vertical direction, i.e. up-and-down and substantially transverse to the direction of plow travel. Two plow blades can be used, they are then vibrated in opposite vertical direction, i.e. one blade is moving “up” when the other is moving “down”. The plow construction is non-standard, necessitating relatively expensive special fabrication of plow components. The efficiency of the constructions seems to be limited in respect to what a randomly vibrating plow is capable of.

[0011] A further type of vibrating plow is described in U.S. Pat. No. 5,281,054 and U.S. Pat. No. 5,392,541. A plow blade is held in a holder, pivotably around an axis preferably located in front of the plow blade cutting edge in the travel direction of the plow. A vibrator is arranged on a cantilever to impart a vertical and arcuate movement to a ripper tooth arranged at a lower end of the plow cutting edge. The plow construction is non-standard, necessitating relatively expensive special fabrication of plow components.

[0012] There is thus a need for apparatus which would permit the height of the blade with respect to the blade holder, and thus the depth of the trench, to be varied readily by the operator, preferably from within the tractor cab, while also performing a controlled vibration movement of the plow blade.

SUMMARY OF THE INVENTION

[0013] It is an object of the invention to provide a plow cable/pipe laying apparatus, which has an enhanced vibration movement of the plow in a substantially forward-backward motion.

[0014] A further object of the invention is to provide a trenching plow, which is adjustable height-wise in its plow holder.

[0015] In the invention, a plow trenching apparatus for a vehicle is described, the plow trenching apparatus comprising a vehicle having a raisable boom and a trenching plow pivotally mounted at a distal end of the boom in a plow holder, to extend rearwardly and downwardly therefrom. The plow has an upper portion and a lower portion, with a forwardly protruding toe portion, and a forward facing cutting portion. The plow is pivotable in the holder about a pivot bar located behind the holder and behind the plow, as seen in the travel direction of the plow during operation. A pivoting motion is imparted to the plow by a vibrator arranged at the upper portion. The vibrator is arranged to impart vibrations generally in a vertical plane, so that the lower portion is pivoted generally back and forth in the travel direction.

[0016] The vibrator is advantageously arranged behind or in front of the upper portion. If the vibrator is placed in front of the upper portion of the plow, there might be problems with interference between the vibrator and the plow holder at certain plow blade settings, though.

[0017] The vibrator preferably has two eccentric weights, each being rotatable around its axis in a plane, and the two weights being synchronized in their rotation so that they pass and are 180 degrees apart at two points during the rotation. This arrangement creates a straight line oscillating motion in the plane.

[0018] Advantageously, the pivot bar is located substantially at the middle of the plow, i.e. the length of the upper portion being substantially equal to the length of the lower portion of the plow.

[0019] Advantageously, an actuation means is connected between the blade holder and the plow blade for varying the position of the plow blade within the blade holder and thereby varying the depth of the blade. The actuation means preferably comprises at least one hydraulic cylinder connected between the blade holder and the plow blade.

[0020] The invention yields an improved apparatus for adjusting the height of a trenching blade in trenching equipment combined with providing a trenching plow having a simple construction, making it cheap to manufacture and maintain. The movement imparted to the plow, being directed mainly forwards in the direction of travel, enhances the efficiency of the plow, thus lowering the requirements on the vehicle regarding strength and pulling power. Desirable attributes of the invention further include obviation of the need to remove the blade or any related parts in order to reset its height, thereby enabling height adjustments to be made by the vehicle operatorfrom a position remote from the blade, and a significant reduction of the time required to make adjustments to the blade height, which enables changes in depth of a ground cut to be made more readily and more economically than can be done using devices of the prior art.

[0021] By using standard components, with the addition of the pivot bar and its mount on the plow holder, the vibrating plow trencher according to the invention can be retrofitted on existing trenching plows without complicated rebuilding or special parts manufacture.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order that the invention may be more clearly understood, the preferred embodiment thereof will now be described in detail by way of example, with reference to the accompanying drawings, in which:

[0023]FIG. 1 is a side view of a vehicle having a trenching plow with a vibrating mechanism according to a first embodiment of the invention, attached to the vehicle;

[0024]FIG. 2 is a top view of the vehicle of FIG. 1;

[0025]FIG. 3A is a side view of a trenching plow with a vibrating mechanism according to FIG. 1, having the vibrator behind of the plow;

[0026]FIG. 3B is a side view of a trenching plow with a vibrating mechanism according to a further embodiment of the invention, having the vibrator in front of the plow;

[0027]FIG. 4 is a side view of the trenching plow of FIG. 1, showing the throw of the plow at its extreme positions in forward and backward vibration movement, respectively;

[0028]FIG. 5 is a partially sectioned top view of a vibrator used in the invention; and

[0029]FIG. 6 is an elevational rear side view of a second embodiment of the invention, showing the plow blade being raisable and lowerable in its holder.

DETAILED DESCRIPTION OF THE INVENTION

[0030] Referring to FIG. 1, there is a blade holder 3′ having a generally vertical channel defined therein, and support means 3 for carrying the blade holder behind a pulling vehicle such as a bulldozer or tractor 2 at a height above the ground. A trenching blade 4 for dragging through the ground behind the vehicle has a shank portion 7 extending upwardly therefrom into the channel and slidably engaging in the channel for vertical movement therewithin, whereby the depth of the blade may be varied. Actuation means, preferably in the form of a least one actuator means 19, for example a hydraulic cylinder (see FIG. 6), is advantageously connected between the blade holder and the blade shank for varying the position of the blade shank within the blade holder and thereby varying the depth of the blade.

[0031] In the preferred embodiment, the support means 3 is at the end of a boom assembly 8, for example including upper and lower linkage arms. The boom is raisable and lowerable via a hydraulic lift cylinder or cylinders 10 between a raised transport position and a lowered operating position in which the link arms preferably are approximately horizontal for maximum pulling power and efficiency. The boom is pivotally connected to the vehicle 2 for pivotal movement about a generally vertical axis, though it is lockable as desired for travelling, for example, and the blade holder 3′ is pivotally mounted to the support means, for pivotal movement about a generally vertical axis. The blade holder pivots with respect to the support means about a plow pivot axis. The boom pivots with respect to the vehicle about a boom pivot axis. The boom can be locked for travel so that it is not free to pivot.

[0032] There is additionally at least one hydraulic cylinder connected between the blade holder 3′ and the support means 3, for varying the angle in the horizontal plane between the blade holder and the support means, whereby the angle of the trenching blade may be varied to steer the movement of the blade through the ground. Actuating the cylinder changes the angle of the blade holder with respect to the support means in the horizontal plane, and because the boom assembly is free to swing, this permits the operator to steer the blade around rocks, tree stumps or other obstacles.

[0033] In the tractor cab, the operator thus has hydraulic controls which give full control over the operation of the trenching blade, i.e. the boom assembly can be raised and lowered between the travelling and operating positions, the blade itself can be raised and lowered within the blade holder, and the blade can be steered.

[0034] FIGS. 1 to 3A and 4 show a first embodiment of a plow trenching device 1 for a vehicle 2 according to the invention. The vehicle has a raisable boom 8 and a trenching plow 4 pivotally mounted at a distal end of the boom in a plow holder 3′, so that the plow extends rearwardly and downwardly therefrom with respect to the travel direction of the vehicle. The boom is preferably attached to the vehicle via a vehicle mount 9 and raisable using, for example, hydraulic cylinders 10. The plow holder is connected to the boom via a pivot means 3, for hingedly pivoting the plow so that the rear of the plow can be pivoted out from the longitudinal direction of the vehicle to either side a predetermined distance. The plow has an upper portion 7 and a lower portion 5, with a forwardly protruding toe portion 5′, and a forward facing cutting portion 6. The plow is pivotable in the holder about a pivot bar 12, preferably located behind the holder and behind the plow, as seen in the travel direction of the plow during operation. The pivot bar is advantageously located substantially at the middle of the plow, i.e. the length of the upper portion being substantially equal to the length of the lower portion of the plow. A pivoting motion is imparted to the plow by a vibrator 11 arranged at the upper portion. The vibrator is arranged to impart vibrations generally in a vertical plane, so that the lower portion is pivoted generally back and forth in the travel direction. The pivoting motion is typically up to about 5 degrees.

[0035] The vibrator 11 is advantageously arranged behind (as shown in FIG. 3A) or in front of (as shown in FIG. 3B) the upper portion. By locating it in any of these ways, the back and forth vibrations generated will rock the plow back and forth, to impart the desired movement to the plow.

[0036] The vibrator 11 preferably has two eccentric weights 17, 18, respectively, each being rotatable around its shaft 15, 16, respectively in a plane. The rotation is provided by a motor 11′, for example a hydraulic motor. The two weights are synchronized in their rotation so that they pass adjacent each other and are 180 degrees apart at two points during the rotation. The weights do not collide since they are at different axial positions along their respective shafts. This arrangement creates a straight line oscillating motion in the plane. Preferably, the weights are enclosed inside a vibrator housing 14, to prevent any accidents when the weights are rotating.

[0037] Using the actuator means 19 to raise or lower the plow blade with respect to the pivot bar 12, will permit the easy adjustment of the pivot characteristics of the blade. If the lower portion of the blade is long, with respect to the upper portion (i.e. the part of the plow that is located above the pivot bar), the vibrations will be relatively small. If the lower portion of the blade is short, with respect to the upper portion, the vibrations will be relatively larger.

[0038] It will be appreciated that the above description relates to the preferred embodiments by way of example only. Many variations on the invention will be obvious to those knowledgeable in the field, and such obvious variations are within the scope of the invention as described and claimed, whether or not expressly described.

[0039] For example, one obvious variation would be to employ two hydraulic cylinders instead of one for raising and lowering the blade, namely one cylinder positioned on each side of the blade holder. 

What is claimed as the invention is:
 1. A plow trenching apparatus comprising: a vehicle having a raisable and lowerable boom; a trenching plow pivotally mounted at a distal end of said boom in a plow holder, to extend rearwardly and downwardly therefrom, said plow having an upper portion and a lower portion with a forwardly protruding toe portion and a forward facing cutting portion, wherein said plow is pivotable in said holder about a pivot bar located on said holder behind said plow as seen in the travel direction of the plow during operation, a pivoting motion being imparted to said plow by a vibrator arranged at said upper portion, said vibrator being arranged to impart vibrations generally in a vertical plane, so that said lower portion is pivoted generally back and forth in the travel direction.
 2. The plow trenching apparatus as recited in claim 1, wherein said pivot bar is located substantially at the middle of the plow, i.e. the length of the upper portion being substantially equal to the length of the lower portion of the plow.
 3. The plow trenching apparatus as recited in claim 1, wherein said vibrator is arranged behind said upper portion.
 4. The plow trenching apparatus as recited in claim 1, wherein said vibrator is arranged in front of said upper portion.
 5. The plow trenching apparatus as recited in claim 1, wherein said vibrator has two eccentric weights, each weight being rotatable around its axis in a plane, said two weights being synchronized in their rotation so that they pass and are 180 degrees apart at two points during the rotation, thereby creating a straight line oscillating motion in said plane.
 6. The plow trenching apparatus as recited in claim 2, wherein said vibrator has two eccentric weighs each being rotatable around its axis in a plane, said two weights being synchronized in their rotation so that they pass and are 180 degrees apart at two points during the rotation, thereby creating a straight line oscillating motion in said plane.
 7. The plow trenching apparatus as recited in claim 3, wherein said vibrator has two eccentric weighs each being rotatable around its axis in a plane, said two weights being synchronized in their rotation so that they pass and are 180 degrees apart at two points during the rotation, thereby creating a straight line oscillating motion in said plane.
 8. The plow trenching apparatus as recited in claim 4, wherein said vibrator has two eccentric weights, each weight being rotatable around its axis in a plane, said two weights being synchronized in their rotation so that they pass and are 180 degrees apart at two points during the rotation, thereby creating a straight line oscillating motion in said plane.
 9. The plow trenching apparatus as recited in claim 1, wherein an actuation means is connected between said blade holder and said plow blade for varying the position of said plow blade within said blade holder and thereby varying the depth of said blade.
 10. The plow trenching apparatus as recited in claim 9, wherein said actuation means comprises at least one hydraulic cylinder connected between said blade holder and said plow blade. 